Prognostic Value of Conventional and Modified Naples Scores for In-Hospital Mortality in Patients with Non-ST-Elevation Acute Coronary Syndrome

Background and Objectives: Inflammation and nutritional status are closely associated with prognosis in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS). This study compared the prognostic performance of the conventional Naples score and CRP-modified Naples score for predicting in-hospital mortality. Materials and Methods: This retrospective, single-center study included 921 patients with NSTE-ACS undergoing percutaneous coronary intervention. Multivariable logistic regression, ROC analysis, reclassification indices, restricted cubic spline analysis, and decision curve analysis were performed. Results: In-hospital mortality occurred in 79 patients (8.6%). Patients who died had higher Naples score and modified Naples score values than survivors. In multivariable models adjusted for baseline clinical variables and GRACE score, both the modified Naples score and conventional Naples score remained independently associated with in-hospital mortality. The modified Naples score showed an adjusted-OR of 3.85 (95% CI: 2.71–5.48; p < 0.001), whereas the conventional Naples score showed an adjusted-OR of 4.52 (95% CI: 3.05–6.70; p < 0.001). The addition of the modified Naples score improved model performance, with a C-index of 0.819, NRI of 0.741, and IDI of 0.127. Similarly, the conventional Naples score model showed a C-index of 0.827, NRI of 0.843, and IDI of 0.125. In ROC analysis, the AUC was 0.701 for the modified Naples score and 0.683 for the conventional Naples score, without a statistically significant difference between them (ΔAUC = 0.017; p = 0.300). Decision curve analysis showed positive net clinical benefit for both scores, with no consistent superiority of either score. Conclusions: Both Naples-based scores were independently associated with in-hospital mortality and provided comparable prognostic performance in patients with NSTE-ACS undergoing PCI.